According to Manuel's database query, there have been 618 different board names logging in within the last 7 days. If you figure that some people use multiple board names, I'd guess that about 575 of those names are unique people.

So around 575 different people per week check these boards. That's about a quarter of the Avlis playerbase!

Conclusion on advertisement banners (NOT popups), it's probably worth doing, but it will probably not make any money, except to encourage people to join fanfic because it removes the banners when you do.

The Bridgekeeper vs King Arthur:
"WHAT...is your name?"
"Arthur, King of the Brits."
"WHAT...is your quest?"
"To find the Holy Grail."
"WHAT...is the average speed of a swallow?"
"An African or a European one?"
"Well I don't knooAAAARGH!"

Bedevere feat. Arthur:
"How do know so much about swallows?"
"Well, you have to know these things when you're a king, you know."

bearing in mind i have no idea how much it would make have you thought about adsense from google? its free and seeing as we spend half our lives on this webpage and the other half on google we could combine and ensure that we never leave....